Add elements of given arrays with given constraints

Given two integer arrays, add their elements into third array by satisfying following constraints –

1. Addition should be done starting from 0th index of both arrays.
2. Split the sum if it is a not a single digit number and store the digits in adjacent locations in output array.
3. Output array should accommodate any remaining digits of larger input array.

Examples:

Input: 
a = [9, 2, 3, 7, 9, 6]
b = [3, 1, 4, 7, 8, 7, 6, 9]
Output: 
[1, 2, 3, 7, 1, 4, 1, 7, 1, 3, 6, 9]

Input:     
a = [9343, 2, 3, 7, 9, 6]
b = [34, 11, 4, 7, 8, 7, 6, 99]
Output: 
[9, 3, 7, 7, 1, 3, 7, 1, 4, 1, 7, 1, 3, 6, 9, 9]

Input:     
a = []
b = [11, 2, 3 ]
Output: 
[1, 1, 2, 3 ]

Input: 
a = [9, 8, 7, 6, 5, 4, 3, 2, 1]
b = [1, 2, 3, 4, 5, 6, 7, 8, 9]
Output: 
[1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0]

Difficulty Level: Rookie

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

The idea is very simple. We maintain an output array and run a loop from the 0th index of both arrays. For each iteration of loop, we consider next elements in both arrays and add them. If the sum is greater than 9, we push the individual digits of the sum to output array else we push the sum itself. Finally we push the remaining elements of larger input array to output array.

Below is the implementation of above idea –

C++

// C++ program to add two arrays following given 
// constraints 
#include<bits/stdc++.h> 
using namespace std; 
  
// Function to push individual digits of a number 
// to output vector from left to right 
void split(int num, vector<int> &out) 
{ 
    vector<int> arr; 
    while (num) 
    { 
        arr.push_back(num%10); 
        num = num/10; 
    } 
    // reverse the vector arr and append it to output vector 
    out.insert(out.end(), arr.rbegin(), arr.rend()); 
} 
  
// Function to add two arrays keeping given 
// constraints 
void addArrays(int arr1[], int arr2[], int m, int n) 
{ 
    // create a vector to store output 
    vector<int> out; 
  
    // maintain a variable to store current index in 
    // both arrays 
    int i = 0; 
  
    // loop till arr1 or arr2 runs out 
    while (i < m && i < n) 
    { 
        // read next elements from both arrays and 
        // add them 
        int sum = arr1[i] + arr2[i]; 
  
        // if sum is single digit number 
        if (sum < 10) 
            out.push_back(sum); 
  
        else
        { 
            // if sum is not a single digit number, push 
            // individual digits to output vector 
            split(sum, out); 
        } 
  
        // increment to next index 
        i++; 
    } 
  
    // push remaining elements of first input array 
    // (if any) to output vector 
    while (i < m) 
        split(arr1[i++], out); 
  
    // push remaining elements of second input array 
    // (if any) to output vector 
    while (i < n) 
        split(arr2[i++], out); 
  
    // print the output vector 
    for (int x : out) 
        cout << x << " "; 
} 
  
// Driver code 
int main() 
{ 
    int arr1[] = {9343, 2, 3, 7, 9, 6}; 
    int arr2[] = {34, 11, 4, 7, 8, 7, 6, 99}; 
  
    int m = sizeof(arr1) / sizeof(arr1[0]); 
    int n = sizeof(arr2) / sizeof(arr2[0]); 
  
    addArrays(arr1, arr2, m, n); 
  
    return 0; 
} 

Java

// Java program to add two arrays following given  
// constraints  
import java.util.Vector; 
  
class GFG 
{ 
  
    // Function to push individual digits of a number 
    // to output vector from left to right 
    static void split(int num, Vector<Integer> out)  
    { 
        Vector<Integer> arr = new Vector<>(); 
        while (num > 0) 
        { 
            arr.add(num % 10); 
            num /= 10; 
        } 
  
        // reverse the vector arr and 
        // append it to output vector 
        for (int i = arr.size() - 1; i >= 0; i--) 
            out.add(arr.elementAt(i)); 
    } 
  
    // Function to add two arrays keeping given 
    // constraints 
    static void addArrays(int[] arr1, int[] arr2, 
                          int m, int n)  
    { 
  
        // create a vector to store output 
        Vector<Integer> out = new Vector<>(); 
  
        // maintain a variable to store 
        //  current index in both arrays 
        int i = 0; 
  
        // loop till arr1 or arr2 runs out 
        while (i < m && i < n)  
        { 
  
            // read next elements from both arrays  
            // and add them 
            int sum = arr1[i] + arr2[i]; 
  
            // if sum is single digit number 
            if (sum < 10) 
                out.add(sum); 
            else
  
                // if sum is not a single digit number,  
                // push individual digits to output vector 
                split(sum, out); 
  
            // increment to next index 
            i++; 
        } 
  
        // push remaining elements of first input array 
        // (if any) to output vector 
        while (i < m) 
            split(arr1[i++], out); 
  
        // push remaining elements of second input array 
        // (if any) to output vector 
        while (i < n) 
            split(arr2[i++], out); 
  
        // print the output vector 
        for (int x : out) 
            System.out.print(x + " "); 
    } 
  
    // Driver Code 
    public static void main(String[] args)  
    { 
        int[] arr1 = { 9343, 2, 3, 7, 9, 6 }; 
        int[] arr2 = { 34, 11, 4, 7, 8, 7, 6, 99 }; 
  
        int m = arr1.length; 
        int n = arr2.length; 
  
        addArrays(arr1, arr2, m, n); 
    } 
} 
  
// This code is contributed by 
// sanjeev2552 

C#

// C# program to add two arrays following given  
// constraints  
using System; 
using System.Collections.Generic; 
  
class GFG  
{  
  
    // Function to push individual digits of a number  
    // to output vector from left to right  
    static void split(int num, List<int> outs)  
    {  
        List<int> arr = new List<int>();  
        while (num > 0)  
        {  
            arr.Add(num % 10);  
            num /= 10;  
        }  
  
        // reverse the vector arr and  
        // append it to output vector  
        for (int i = arr.Count - 1; i >= 0; i--)  
            outs.Add(arr[i]);  
    }  
  
    // Function to add two arrays keeping given  
    // constraints  
    static void addArrays(int[] arr1, int[] arr2,  
                        int m, int n)  
    {  
  
        // create a vector to store output  
        List<int> outs = new List<int>();  
  
        // maintain a variable to store  
        // current index in both arrays  
        int i = 0;  
  
        // loop till arr1 or arr2 runs out  
        while (i < m && i < n)  
        {  
  
            // read next elements from both arrays  
            // and add them  
            int sum = arr1[i] + arr2[i];  
  
            // if sum is single digit number  
            if (sum < 10)  
                outs.Add(sum);  
            else
  
                // if sum is not a single digit number,  
                // push individual digits to output vector  
                split(sum, outs);  
  
            // increment to next index  
            i++;  
        }  
  
        // push remaining elements of first input array  
        // (if any) to output vector  
        while (i < m)  
            split(arr1[i++], outs);  
  
        // push remaining elements of second input array  
        // (if any) to output vector  
        while (i < n)  
            split(arr2[i++], outs);  
  
        // print the output vector  
        foreach (int x in outs)  
            Console.Write(x + " ");  
    }  
  
    // Driver Code  
    public static void Main(String[] args)  
    {  
        int[] arr1 = { 9343, 2, 3, 7, 9, 6 };  
        int[] arr2 = { 34, 11, 4, 7, 8, 7, 6, 99 };  
  
        int m = arr1.Length;  
        int n = arr2.Length;  
  
        addArrays(arr1, arr2, m, n);  
    }  
}  
  
// This code is contributed by PrinciRaj1992 

Output:

9 3 7 7 1 3 7 1 4 1 7 1 3 6 9 9

Time complexity of above solution is O(m + n) as we traverses both arrays exactly once.

This article is contributed by Aditya Goel. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.

My Personal Notes

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

C++

Java

C#

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